Engine starting apparatus



March 14, l RIFRElTAG AL ENGINE STARTING APPARATUS FiledrOcf. 6, 1957 2 Sheets-Sheet 1 M alh 14,' 1944. R. FREITAG ETAL 344983 ENGINE STARTING APPARATUS l Filed Oct. 6. 1937 2 SheetsSheet 2 Fig-5 lflIIIIllllIllllllllllllllllllZl,

/N VE N T035' vA rbe/VEY Patented Mar. 14, 1944 ENGINE STARTING APPARATUS Reinhold Freitag, StuttgartUnterturkheim, and

Will Stoeckicht, Solln, near Munich, Germany; vested in the Alien Property Custodian Application October 6, 1937, Serial No. 167,568 In Germany October 10, 1935 22 Claims.

In the driving means for propellers hitherto known the shaft of the propeller is coupled to the engine shaft either directly or by a few gear wheels Vand at starting the starter is caused to act directly upon the engine shaft.

In contrast thereto the present invention resides in a method foi` the starting of internal combustion engines driving propellers, blower blades or other rotating masses according to which the starter is caused to act upon the uncoupled propeller shaft and the propeller shaft is coupled to the engine shaft only when so much energy of rotation has been accumulated in the mass formed by the propeller shaft and blades that this is capable of turning over the internal combustion engine. This method :may also be applied in such fashion that the starter is first caused to act upon the uncoupled propeller shaft and somewhat later, immediately before the coupling thereof, also and at the same time upon the engine shaft.

By this new starting method, not only the starter but also the parts to .be driven are greatly spared because the transmission of the starting forces and also the initiation of the drive from the engine take place extremely gently. In particular the starter clutch is subjected to no such high wear as hitherto and the starter clutch does not need to be repeatedly renewed. Also it is possible to employ a considerably smaller and simpler starter than hitherto which again represents a saving of Weight and starting energy.

Generally speaking, this invention may be delined as comprising the constructions and combinations recited in the annexed claims and illustrated in certain embodiments in the drawings accompanying yand forming a part of this application, wherein:

Fig. 1 is a longitudinal view, partially in crosssection, illustrating the application of one form of starting apparatus to an internal combustion engine driving a propeller;

Fig. 2 is a partial longitudinal cross-sectional view, similar to Fig. l, of a modified for-m of starting apparatus;

Fig. 3 is a detail illustration of a braking device in side elevation and section;

Fig. 4 a self acting dog clutch in longitudinal section and detail illustration;

Fig. 5 is a partial longitudinal oross-sectional view on an enlarged scale, illustrating a further modification of the starting apparatus in which the over-running clutch directly interconnects the engine and propeller shafts;

Fig. 6 diagrammatically illustrates an arrangement whereby the action of the brake on the starting apparatus may be correlated with the actuation of the starting motor;

Fig. 7 is a further arrangement, similar to Fig. 6, wherein the actuation of the brake on the starting apparatus is brought about in response to the starting motor current; vand Fig. 8 illustrates an adjustable pitch propeller for use in connection with the starting system such as illustrated in Figs. 1, 2 and 5.

In Fig. 1 a driving engine-shaft I and a pr0- peller shaft 2 to be driven are located coaXially one behind the other. The two shafts have each a flange-disc, 3 and Il respectively and near the respective edges of each flange-disc, Fig. 1 shows pins 5 and S of which there are about six in all. Each of the pins carries a respective planet wheel shown at 'I and 8. For these planet wheels 1, 8 there is provided a common sun-wheel body S which lbridges both the axial distance and also the radial distance between the same in such fashion that the planet wheels 'I engage in internal teeth il) and the planet Wheels 8 in external teeth II. The sun-wheel body S has generally the shape of a bell and is mounted in freely rotatable fashion on the shaft I. The planet wheels I also engage with a pinion I2 which is likewise mounted freely on the shaft I. Also freely mounted on the shaft and rigidly connected to the wheel I2 is a braking drum I3 ywhose braking band lil (Fig. 3) can be tightened or loosened by a lever I6 swingable about a pivot I5. Engaged with the lever i5 is the rod I'I of a piston I8 which slides ina cylinder I9 and is influenced on the one hand :by oil pressure 2l) and on the other hand by a spring 2I. The oil flows to the chamber 2i] in front of the piston through a passage 22 in which a throttling and closure valve 23 is included. A return passage 24 branches from the valve 23. The valve 23 can be adjusted by a lever 25 in such fashion that the oil flow from the passage 22 to the oil chamber 28 is either cut off completely or is only throttled to such an extent that the oil pressure suffices to overcome the stress in the spring 2l and forcibly to tighten the :braking lband I4. The excess oil then flows through the passage 24 back to the place from which it was taken. Finally the sun-wheel body has a further ring of external teeth 26 in which a toothed wheel 21 engages. The wheel 2l is in turn in engagement with a toothed wheel 28 -Which is mounted on the shaft of a liquid pump 29 which supplies pressure oil through the passage 22 to the cylinder space 20 in front of the piston I8. At the end,

of the pump shaft there is also mounted a clutchhalf 3D in the vicinity of a corresponding clutchhalf 3| of a Starter 32. Finally there is also provided a further stationary toothed ring 33 with internal teeth in which the planet wheels 8 roll. Also a clutch-half 34 (Fig. 4) is provided on the end of the engine shaft I towards the propeller shaft 2. The complementary coacting half 35 is mounted slidably in the sun-wheel body 9 in such fashion that it moves against the clutchhalf 34 and engages it as soon as the sun-wheel body 9 rotates more slowly than the engine shaft.

For this purpose the clutch ring 36 carrying the dog teeth 35 is mounted, non-rotatably but guided by grooves 3'I parallel to the principal axis, in axially movable fashion on the sun-wheel body 9. On the outside of the clutch ring 36'is va ring of inclined grooves or a kind of flat thread-teeth 33 which engage in corresponding teeth 39. teeth 39 are cut in a bushing 4I] which is pressed with a frictionally tight fit by a spring 4| against a recess 42 in the engine shaft I.

The manipulation and the manner of operation of the arrangement in accordance with the invention is as follows: I

As starter 32 there is provided a y wheel starter of such construction that as long as this is actuated or this alone is the driving part, its clutch-part 3| is in the engaged position and when it has fulfilled its purpose, it springs again into the disengaged position.

Upon actuation of the starter 32, therefore, the clutch parts 30, 3| come into engagement and the wheel 28 together with the pump 29 is set in rotation, for example in the clockwise direction. Consequently the intermediate wheel 2`| rotates in the opposite direction and the sunwheel body 9 in the same direction. Consequently the planet wheels 'I also rotate in the clockwise direction and the toothed wheel I2 mounted freely on the shaft I in the opposite direction, provided that the brake is not applied as is initially the case at starting. The wheels 'I and I2 rotate idly and the engine shaft I remains initially unaffected. The sun-wheel body 9 yalso drives the planet wheels 8 which rotate counterclockwise and roll on the stationaly ring'of Ateeth 33.- By this means the pivots E of the planet wheels 8 are carried along in the clockwise direction and the screw shaft 2 likewise rotates in the clockwise direction and thus, due to the rotary mass constituted by, the propeller blades, the flange-disc 4 and the other rotating gear parts, accumulates a considerable kinetic energy.

The liquid pump 29 also commences to rotate at the same time as the gear wheel 28 and, with the valve 23 open, supplies pressure oil through the passage 22 to the chamber 20 in the cylinder I9 with the result that directly after the rpropeller shaft has received a first powerful driving impulse, the piston I8 is displaced to the right against the force of its spring 2| and consequently the .braking band is tightened, that is the wheel I2 is braked and brought to rest. As a result the planet wheels 'I driven by the sun-wheel sbody 9 and rolling on the now stationary wheel |2-acting at their pivots 5-also set the engine shaft I in rotation and this likewise in the clockwise direction.

The power transmitted from the starter 32 to the engine shaft I then increases in the same measure as the rapidly and steadily increasing braking force on the drum I3. On the other' hand the loading on the starter 32 also increases until nally it is no longer capable of driving the The gearing and the engine and its rotation commences to become slower. Consequently, working backwardly, the rotating propeller shaft 2 and the parts rotating with it also commence to give up their stored energy to the engine shaft so that now a driving force both from the starter andY also from the propeller shaft :becomes effective upon the engine shaft and this turns over the engine before the action of the starter falls off appreciably. At the instant at which the engine responds, the engine shaft takes over the drive of the gearing and propeller shaft which, in accordance with the example shown in Fig. 1, may take place through two transmission stages depending upon .whether the brake is tightened or released.

With the brake tightened, the sun-wheel body 9 rotates more quickly than the engine shaft I. The clutch 34, 35 remains in its disengaged position since the frictional force between the shaft I and the friction bush 49 (Fig. 4) acts through the teeth 38, 39 upon the clutch ring 36 in such fashion that the latter retains its right hand end position. In this position of the clutch 34, 35 a drive of the screw shaft 2 takes place through the transmission of the planet gearings 1, I 0 and 8, 33.

By moving over the valve 23 by the lever 25 (Fig. 3), however, it is also possible to cause the liquid Varriving through the passage 22 to ilow into the passage 24 and thereby to remove the oil pressure from the piston I8. The spring 2| then eX- pands and displaces the piston I8 into such an end position that the braking band I4 is released and the braking drum I3 can rotate with the wheel I2. From this instant on, the planet wheels 'I and the clutch Wheel I2 also rotate idly with the result that the hitherto higher speed of the sun-wheel body 9 as compared with the speed of the engine shaft falls off and the sun-wheel body therefore rotates more slowly than the said shaft. The result of this is that the frictional pressure in the clutch 34, 35 is converted at the inclined teeth 38, 39 into a push which displaces the clutch ring 36 to the left and the clutch 34, 35 then engages. By this the engine shaft I and the sun-wheel body 9 are rigidly connected together. Consequently the two elements rotate at the same speed. The planet wheels I and the wheel I2 rotate idly therewith and the engine shaft I drives the screw shaft 2 through one transmission only, the teeth II and planet Wheels 8.

Upon renewed tightening of the brake b-y a reversal of the valve 23 in such manner that the full oil pressure can again act on the piston I8 the original condition directly after starting is again established in that a negative drive by way of the planet wheel gearing I0 is again established and consequently the sun-wheel body 9 tends again to rotate more quickly than the engine shaft so that the clutch 34, 35 is again disengaged.

Fig. 2 shows how a further transmission can be interposed between the sun-wheel body 9,;and braking drum I3. In this example the toothed ring I0 does not engage directly with the ,wheel 'I but with a smaller wheel 'la arranged in front thereof and rigidly coupled therewith. In.order to obviate the greater constructional lengthV necessitated by the inclusion of the Wheel 'la the braking ring of the drum I3 is in this example directed towards the lbell 9. Otherwise the arrangement in accordance with Fig. 2 operates precisely as does that of Fig. 1. Within the scope of the invention, the brake may be constructed in any desired fashion. In place of the band brake, a liquid brake, a pneumatic brake oran electric brake or any other suitable clutch device may be provided. The particular construction of the over-running clutch between the engine and propeller shaft may likewise be as desired. In some cases, the over-running clutch may also directly connect the two shafts. Such an arrangement is illustrated lby way of example in Fig. 5 Iwhich is similar to Fig. 4, except that the groove 37 for guiding the clutch ring 36 are formed on the propeller shaft 2. In this case the sun-wheel body 9 is simply mounted relatively to the shaft 2 by suitable means such as the ball bearing 43.

Also, within the scope of the invention, the

number of planet wheels and the choice of the transmission between starter and gearing and between sun-wheel body and shafts are left free. The gearing of the arrangement in accordance 'with the invention need not essentially be constructed as planet gearing. The manipulating members for the starter may be coupled with the manipulating member for the valve 23 in the passage 22 so that both devices can be actuated by a common main manipulating member. As an example of the manner in which this may be done, attention is directed to Fig. 6 showing the handle 25 of the valve connected by a suitable link 44 with a switch member 45 for starting of the starter motor 32. Upon closure of the switch 45 a circuit will be established for the motor 32 through the contact 45 and conductor 41, and simultaneously the valve will be rotated in such a manner as to apply pressure to the cylinder I9 of the brake control. An extension 43 of the link 44 permits simultaneous manual operation of both the brake and the starter motor.

The pump 29 either draws its oil from a separate Vessel or it is connected to the lubricating oil circulation of the engine. Pressure oil may also be replaced by pressure water, for example cooling water. In the case of the adaptation of the brake for another operating medi-um, the

pump 28 is, naturally, replaced by a suitable Dressureor current-producing device. If an electrical arrangement is provided, the braking current may also be taken from the starter circuit. The braking device may also be designed s that the braking band is tightened from two ends. This may be accomplished by means of the arrangement illustrated in Fig. 7, in which a brake .band tightening solenoid 48 is included in the electrical circuit of the motor 32, and will accordingly be energized simultaneously with energization of this motor. solenoid 48 rotates the lever I6 in such a manner that the ends of the brake band connected at 49 and D will move in such a direction as to tighten the band from both ends.

The provision of the subject of the invention is particularly advantageous for the drive of a variable pitch propeller because with such an arrangement the blades of the propeller may be set right back at starting and the braking effect of air resistance at starting limited to a minimum value. Consequently the inertia energy of the propeller set in rotation can be fully utilised at starting.

Fig, 8 illustrates the propeller blades pivoted at 55 and 56, in full lines for normal use and in dotted lines for starting. The propeller shaft is illustrated as mounted through gears 5l and 52.

The invention may also be employed for the driving of rotary masses upon travelling or stationary engines.

Energization of the While we have herein shown and described onlycertain embodiments of certain features of our present invention, it is to be understood that they are to be regarded merely as illustrative, and that we do not intend to limit ourselves thereto except as may be required by the following claims.

We claim:

l. In an aircraft having an internal combustion engine and a propeller for driving the aircraft, in combination, a sun wheel andv means for connecting the same to said propeller, starting means for initiating rotation of said sun wheel, a drive shaft for said engine, planetary gearing interconnecting said sun wheel and said drive shaft, adjustable braking means on said planetary gearing for controlling the action of the propeller and the starting means upon said drive shaft, and an overrunning clutch between said drive shaft and said sun wheel.

2. In combination, an internal combustion engine having a drive shaft, a rotatably mounted mass, a rotatably mounted shell, a prime mover, means for connecting said shell for rotation by said prime mover, planetary gearing including a relatively stationary gear intermediate said shell and said rotatably mounted mass, planetary gearing including a normallyI free gear intermediate said shell and said drive shaft, and means for controlling the movement of said relatively free gear.

3. The combination according to claim 2, in combination with means responsive to the difference in speed between said drive shaft and said shell for directly interconnecting said drive shaft to said shell.

4. In combination, an internal combustion engine having a drive shaft, a brake drum and a gear wheel connected therewith mounted for free rotation on said drive shaft, a shell mounted for free rotation on said drive shaft, said shell having one portion containing an internal annular gear and two other portions each containing external gears, a first pinion connected to said drive shaft and mounted for rotation between said internal annular gear and said gear wheel, means for controlling the rotation of said brake drum, starting means for imparting rotation to said shell through one of said external gears, a propeller, a stationary internal annular gear surrounding the other of said external gears, and a second pinion connected to said propeller and mounted for engagement between said stationary internal gear and its surrounded external gear on said shell.

5. The combination according to claim 4, in combination with an overrunning clutch responsive to a difference in speed between said drive shaft and said shell for directly interconnecting those elements.

6. The combination according to claim 4, in which'the means for controlling the rotation of the brake drum comprises a normally loose brake band mounted on said drum, a fluid-pressure responsive device for tightening said band upon said drum, a pump driven by said starting means for supplying fluid under pressure to said device, and a valve for controlling the flow of said fluid.

7. In engine starting mechanism for aircraft, the combination of an engine shaft, a propeller, a rotatably mounted member, means for rotating said propeller through said member for storing energy in said propeller, connecting means imparting said energy to said engine shaft, means for disabling said connecting means. and means -responsive to a difference in speed between said engine shaft and said member for directly connecting the same together.

8. In engine starting mechanism, the combination of an engine shaft, a propeller, ,a rotatably mounted member, means for rotating said propeller through said member for storing energy in said propeller, connecting means imparting said energy to said engine shaft, means for disabling said connecting means, and an overrunning clutch directly between said engine shaft and said member.

9. In combination with an internal combustion engine having a drive shaft, an aircraft propeller, means for accelerating said propeller to store energy therein with said engine shaft remaining stationary, a freely running planetary gearing intermediate said propeller and shaft, and braking means on said gearing for drivably connecting said propeller and shaft.

10. The combination according to claim 1, in combination with a source of power actuated by said starting means, and a device actuated by said source of power connected for controlling the adjustable braking means.

11. The combination according to claim 2, in

which said last means comprises a braking device on said free` gear, and a source of power driven by said prime mover connected for actuation of said braking device.

12. The combination according to claim 9, in combination with a source of power driven by said acceleration means and connected for actuation of said braking means.

13. The combination according to claim 7, in Which said propeller is of the adjustable blade type.

14. In an engine starting mechanism, the combination of an engine shaft, a propeller, means for starting said propeller, connecting means between said starting means and said engine shaft, means for making and breaking the connection, and additional releasable means for connecting said engine shaft and said propeller.

15. The combination according to claim 21,

in which said connecting means includes means for producing a difference in speed between said engine shaft and said inertia device, andA said releasable connecting means is an over-running clutch automatically releasable upon the inclusion of said connecting means, due to said difference in speed.

16. The combination according to claim 21, in which said connecting means includes means for producing a diierence in speed between said engine shaft and said inertia device, and said releasable connecting means is an over-running clutch, automatically releasable during the starting of said inertia device or the inclusion of said connecting means.

17. The combination according to claim 21, in combination with means interconnecting said starting means and said connecting means for actuating said connecting means upon deenergization of said starting means, and vice versa.

18. The method of starting an internal coinbustion engine of the type adapted to drive a propeller, which includes'the steps bringing the propeller up to a predetermined speed by driving it through an engine starter, then connecting the engineto both the propeller and starter through a releasable driving connection so that it is subjected to the driving force of the starter and the inertia forces of the propeller and then, after the engine has started, releasing the driving connection between the engine and the starter and propeller and substantially simultaneously connecting the engine directly to the propeller independently of the releasable connection.

1'9. The method of starting an internal combustion engine, which includes the steps of bringing a rotatable inertia member up to a predetermined speed by driving it through an engine starter, then connecting the engine to both the inertia device and starter through releasable driving connection so that it is subjected to the driving force of the starter and the inertia forces of the rotatable inertia member, and then after the engine has started, releasing the driving connection between the engine and the inertia member and starter and substantially simultaneously directly connecting the engine to the inertia member independently of the releasable connection.

20. In an engine starting mechanism, the combination of an engine shaft, a rotatably mounted inertiaI device, a rotatably mounted member, starting means for rotating said inertia device through said member for storing energy in said device, connecting means between said starting means and said engine shaft, means for disabling said connecting means, and an overrunning clutch directly between said engine shaft and said member for interconnecting the same independently of the means for rotating said inertia device.

21. In an engine starting mechanism, the combination of an engine shaft, a rotatably mounted inertia device, means for starting said inertia device, connecting means between said starting means and said engine shaft, means for controlling the making and breaking the connection between said starting meansV and said engine shaft, and releasable means independent of said connecting means, for connecting said engin shaft tosaid inertia device.,

22. In an engine starting mechanism, the combination of an engine shaft, a rotatably mounted inertia device, astarting device for said inertia device, first drivably connecting means between said starting device and said inertia device, second variable drivably connecting means between said rst drivably connecting means and said engine shaft, third drivably connecting means between said engine shaft and said inertia def vice, and means for varying said second drivably connecting means. y

' REINHOLD FREITAG.

WILL STOECKICHT. 

